Photoshop is incredibly useful, popular and powerful program that will help you to adjust, edit and manipulate your images. It is complex and packed with many tools and it can take long time to learn and master. Many photographers however, use only some of those tools avaliable. These are the tools I use most of the time to edit my images.
Adjustment layers apply colour and tonal adjustments to your image. This creates a new layer above your image, but doesn't change the pixel value of the original image, therefore it is a non-destructive method of image editing. All the changes are made and saved in adjustment level. You can change your adjustments later on or even completely discard them. Layers allow for advanced composition via transparency and blending, stacking images or parts of images on the top of one another. Some of the features of layers I use most are Curves and Channel mixer.
Curves tool is one of the most powerful tools in Photoshop. It lets you adjust image brightness and contrast by simply shaping the curve. The great thing about using curves to adjust the tonal value is that it doesn’t just change the value of pixels you are adjusting but also pixels with similar values around it. Shadows are located bottom left and highlights top right. By simply pulling shadows down and highlight up you adjust contrast of your image. Each adjusted value is represented by a little white dot along the line. If you are unhappy with adjustment click the dot and drag it of the screen to delete it. To adjust colour, click RGB box and select from Red, Green or Blue channel. This adjusts respective colours and gives you control over the tonality of your image. I am not using any pre-sets at this stage and I adjust levels until I’m happy with it.
I use the channel mixer to desaturate image or for B&W image conversion. It works the same way as if you were using colour filter with B&W film photography. Even though you are working with B&W media filters only let certain wavelengths through and this will change tones on B&W film. After clicking on Channel mixer icon, a window opens with three sliders for each RGB channel and constant slider. When adjusting RGB channel keep in mind that total value needs to be at 100% otherwise you will change brightness as well. Red channel will give you smoother skin tones or darker sky while the blue channel acts in the opposite way. Blue filter also tends to reduce contrast across the image. Green channel usually adjusts balance between Red and Blue channels.
Clone stamp tool:
The clone stamp tool is used in pixel by pixel cloning. It allows you to duplicate a part of the image. Brush size and shape, opacity, flow and blending modes can all be selected in toolbar panel. Simply select part of an image you’d like to clone, press ALT and click it. Now paint over your image to clone desired parts of it. Clone stamp can be used for covering skin blemishes or removing unwanted parts of an image. It is not my most favorite way of retouching as it will copy/clone exact pixels and after a while of using it you will start seeing repeating patterns in your image. To avoid this problem you can use the healing brush as this will sample more pixels and paints them more randomly.
Healing brush lets you fix distractive image imperfections, blemishes or scratches. I find this to be the best retouching tool in Photoshop. Healing brush does a good job in matching pixels tones and textures and will try to keep it as seamless as possible. To remove simple little blemishes, select size that is just slightly larger than a blemish and click to remove it. Healing brush will look at the pixels around your selection and adjusts it. To correct more pronounced wrinkles or blemishes I would duplicate the layer and remove them completely with the healing brush, then bring the opacity down to reveal some of the original image and thus keeping it looking more natural. I prefer not to create a porcelain looking skin as I want to see how my subject looks in reality and I just aim to tweak the image not change it.
After you have tweaked your photo, you definitely want to sharpen the image to bring back some of that crispness that could have been lost in post pro or adjust slightly out of focus photo. The tool I use for sharpening is called Unsharp Mask. There are three sliders that will determine the sharpness of the image. Radius slider determines how many pixels out from the edge will be affected and Threshold determines how different a pixel must be from surrounding before it is considered a pixel edge. I leave those at the default setting and only adjust the Amount. There is no real rule on how I sharpen images; I will move the slider up until I see the pixels almost falling apart and then back up a little. One thing I make sure I am doing with every image is, that I will view it at 100% then apply Unsharp mask. Also, I will only sharpen the image at the resolution I want to use it and every time I resize the image I will re-sharpen it again. When sharpening you will need to do so on the original image as it will not work on new empty layer as of now.